1) An article of underwear 2) Garment 3) What exactly is a brief 1) Bandeau 2) Bra 3) Brassiere 4) Camisole 5) Chemise 6) Pantie 7) Panty 8) Petticoat 9) Singlet 10) Slip 11) Teddies 12) Underbodice 13) Underclothes 14) Underclothing 15) Underpants 16) Undershirt 17) Underskirt 18) Underwear 19) Vest 
Undergarments are clothes worn under other clothes, often directly next to the skin, but may comprise more than one layer. They keep outer garments from being soiled by bodily secretions and discharges, shape the body, and provide support for parts of it. In cold weather, long underwear is sometimes worn to provide additional warmth. Special types...
[n] - a garment worn under other garments
unmentionable noun a garment worn under other garments
an article of underwear.